This invention relates to a control device for activating a control element which operates another device or machine, as a consequence of the activation of one of two operating elements mounted in parallel and designed to alternatively control said device or machine.
In certain applications, a device or machine is controlled alternatively by one of two operating elements disposed at two different points. One application in which this requirement frequently occurs is that of boats, in which the accelerator and clutch of the boat engine are controlled by one of two operating elements which usually consist of flexible cables which slide within a sheath. This alternative control is obtained substantially by the use of one of two types of device, each of which is positioned between said operating elements and the device or machine which is to be controlled.
A device of a first type comprises substantially a linkage which contains a lever connected at two different points to said two operating elements, and connected at a third point to the device to be controlled, by way of a suitable transmission system.
Devices of this type have fairly low control response and precision, because of the slack between the various parts of the device. This disadvantage is particularly grave when the direction of movement of one of said operating elements is reversed.
A device of a second type, suitable for use when said operating elements consist of flexible cables slideable within a sheath, comprises a frame on which there is a slideable saddle connected both to the cable of one of said two operating elements and to the sheath of the other. The cable of this latter operating element is connected directly to the device to be controlled.
Devices of this second type have the disadvantage of requiring a fairly large force for their operation, because of friction. Furthermore, during activation of the device, the sheath of one of the operating elements moves, with the disadvantage of altering the initial configuration (position and curvature) of the elements themselves.